[ViewVC] Diff of: cvs/AnyEvent-MP/MP.pm

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.41 by root, Sat Aug 8 21:56:29 2009 UTC vs.
Revision 1.79 by root, Fri Sep 4 21:52:09 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
13	$SELF # receiving/own port id in rcv callbacks	12	$SELF # receiving/own port id in rcv callbacks
14		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
15	# ports are message endpoints	17	# ports are message destinations
16		18
17	# sending messages	19	# sending messages
18	snd $port, type => data...;	20	snd $port, type => data...;
19	snd $port, @msg;	21	snd $port, @msg;
20	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
21		23
22	# miniports	24	# creating/using ports, the simple way
23	my $miniport = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
24		26
25	# full ports	27	# creating/using ports, tagged message matching
26	my $port = port;	28	my $port = port;
27	rcv $port, smartmatch => $cb->(@msg);
28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
29	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
30		31
31	# remote ports	32	# create a port on another node
32	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
33
34	# more, smarter, matches (_any_ is exported by this module)
35	rcv $port, [child_died => $pid] => sub { ...
36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
37		34
38	# monitoring	35	# monitoring
39	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $port, $cb->(@msg) # callback is invoked on death
40	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
42		39
		40	=head1 CURRENT STATUS
		41
		42	bin/aemp - stable.
		43	AnyEvent::MP - stable API, should work.
		44	AnyEvent::MP::Intro - explains most concepts.
		45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
		47
		48	stay tuned.
		49
43	=head1 DESCRIPTION	50	=head1 DESCRIPTION
44		51
45	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
46		53
47	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
48	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
49		56
50	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
51	manual page.	58	manual page and the examples under F<eg/>.
52
53	At the moment, this module family is severly broken and underdocumented,
54	so do not use. This was uploaded mainly to reserve the CPAN namespace -
55	stay tuned! The basic API should be finished, however.
56		59
57	=head1 CONCEPTS	60	=head1 CONCEPTS
58		61
59	=over 4	62	=over 4
60		63
61	=item port	64	=item port
62		65
63	A port is something you can send messages to (with the C<snd> function).	66	Not to be confused with a TCP port, a "port" is something you can send
		67	messages to (with the C<snd> function).
64		68
65	Some ports allow you to register C<rcv> handlers that can match specific	69	Ports allow you to register C<rcv> handlers that can match all or just
66	messages. All C<rcv> handlers will receive messages they match, messages	70	some messages. Messages send to ports will not be queued, regardless of
67	will not be queued.	71	anything was listening for them or not.
68		72
69	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
70		74
71	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	75	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
72	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
73	exception is the the node port, whose ID is identical to its node
74	reference.
75		77
76	=item node	78	=item node
77		79
78	A node is a single process containing at least one port - the node	80	A node is a single process containing at least one port - the node port,
79	port. You can send messages to node ports to find existing ports or to	81	which enables nodes to manage each other remotely, and to create new
80	create new ports, among other things.	82	ports.
81		83
82	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
83	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
84		87
85	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[a-za-Z0-9_\-.:]+>
86		89
87	A node reference is a string that either simply identifies the node (for	90	A node ID is a string that uniquely identifies the node within a
88	private and slave nodes), or contains a recipe on how to reach a given	91	network. Depending on the configuration used, node IDs can look like a
89	node (for public nodes).	92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		93	doesn't interpret node IDs in any way.
90		94
91	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
92	TCP/IP, other protocols might look different).
93		96
94	Node references come in two flavours: resolved (containing only numerical	97	Nodes can only talk to each other by creating some kind of connection to
95	addresses) or unresolved (where hostnames are used instead of addresses).	98	each other. To do this, nodes should listen on one or more local transport
		99	endpoints - binds. Currently, only standard C<ip:port> specifications can
		100	be used, which specify TCP ports to listen on.
96		101
97	Before using an unresolved node reference in a message you first have to	102	=item seeds - C<host:port>
98	resolve it.	103
		104	When a node starts, it knows nothing about the network. To teach the node
		105	about the network it first has to contact some other node within the
		106	network. This node is called a seed.
		107
		108	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		109	are expected to be long-running, and at least one of those should always
		110	be available. When nodes run out of connections (e.g. due to a network
		111	error), they try to re-establish connections to some seednodes again to
		112	join the network.
		113
		114	Apart from being sued for seeding, seednodes are not special in any way -
		115	every public node can be a seednode.
99		116
100	=back	117	=back
101		118
102	=head1 VARIABLES/FUNCTIONS	119	=head1 VARIABLES/FUNCTIONS
103		120
…		…
105		122
106	=cut	123	=cut
107		124
108	package AnyEvent::MP;	125	package AnyEvent::MP;
109		126
110	use AnyEvent::MP::Base;	127	use AnyEvent::MP::Kernel;
111		128
112	use common::sense;	129	use common::sense;
113		130
114	use Carp ();	131	use Carp ();
115		132
116	use AE ();	133	use AE ();
117		134
118	use base "Exporter";	135	use base "Exporter";
119		136
120	our $VERSION = '0.1';	137	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		138
121	our @EXPORT = qw(	139	our @EXPORT = qw(
122	NODE $NODE *SELF node_of _any_	140	NODE $NODE *SELF node_of after
123	resolve_node initialise_node	141	configure
124	snd rcv mon kil reg psub spawn	142	snd rcv mon mon_guard kil reg psub spawn
125	port	143	port
126	);	144	);
127		145
128	our $SELF;	146	our $SELF;
129		147
…		…
133	kil $SELF, die => $msg;	151	kil $SELF, die => $msg;
134	}	152	}
135		153
136	=item $thisnode = NODE / $NODE	154	=item $thisnode = NODE / $NODE
137		155
138	The C<NODE> function returns, and the C<$NODE> variable contains	156	The C<NODE> function returns, and the C<$NODE> variable contains, the node
139	the noderef of the local node. The value is initialised by a call	157	ID of the node running in the current process. This value is initialised by
140	to C<become_public> or C<become_slave>, after which all local port	158	a call to C<configure>.
141	identifiers become invalid.
142		159
143	=item $noderef = node_of $port	160	=item $nodeid = node_of $port
144		161
145	Extracts and returns the noderef from a portid or a noderef.	162	Extracts and returns the node ID from a port ID or a node ID.
146		163
147	=item initialise_node $noderef, $seednode, $seednode...	164	=item configure $profile, key => value...
148		165
149	=item initialise_node "slave/", $master, $master...	166	=item configure key => value...
150		167
151	Before a node can talk to other nodes on the network it has to initialise	168	Before a node can talk to other nodes on the network (i.e. enter
152	itself - the minimum a node needs to know is it's own name, and optionally	169	"distributed mode") it has to configure itself - the minimum a node needs
153	it should know the noderefs of some other nodes in the network.	170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
154		172
155	This function initialises a node - it must be called exactly once (or	173	This function configures a node - it must be called exactly once (or
156	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
157		175
158	All arguments are noderefs, which can be either resolved or unresolved.
159
160	There are two types of networked nodes, public nodes and slave nodes:
161
162	=over 4	176	=over 4
163		177
164	=item public nodes	178	=item step 1, gathering configuration from profiles
165		179
166	For public nodes, C<$noderef> must either be a (possibly unresolved)	180	The function first looks up a profile in the aemp configuration (see the
167	noderef, in which case it will be resolved, or C<undef> (or missing), in	181	L<aemp> commandline utility). The profile name can be specified via the
168	which case the noderef will be guessed.	182	named C<profile> parameter or can simply be the first parameter). If it is
		183	missing, then the nodename (F<uname -n>) will be used as profile name.
169		184
170	Afterwards, the node will bind itself on all endpoints and try to connect	185	The profile data is then gathered as follows:
171	to all additional C<$seednodes> that are specified. Seednodes are optional
172	and can be used to quickly bootstrap the node into an existing network.
173		186
174	=item slave nodes	187	First, all remaining key => value pairs (all of which are conveniently
		188	undocumented at the moment) will be interpreted as configuration
		189	data. Then they will be overwritten by any values specified in the global
		190	default configuration (see the F<aemp> utility), then the chain of
		191	profiles chosen by the profile name (and any C<parent> attributes).
175		192
176	When the C<$noderef> is the special string C<slave/>, then the node will	193	That means that the values specified in the profile have highest priority
177	become a slave node. Slave nodes cannot be contacted from outside and will	194	and the values specified directly via C<configure> have lowest priority,
178	route most of their traffic to the master node that they attach to.	195	and can only be used to specify defaults.
179		196
180	At least one additional noderef is required: The node will try to connect	197	If the profile specifies a node ID, then this will become the node ID of
181	to all of them and will become a slave attached to the first node it can	198	this process. If not, then the profile name will be used as node ID. The
182	successfully connect to.	199	special node ID of C<anon/> will be replaced by a random node ID.
		200
		201	=item step 2, bind listener sockets
		202
		203	The next step is to look up the binds in the profile, followed by binding
		204	aemp protocol listeners on all binds specified (it is possible and valid
		205	to have no binds, meaning that the node cannot be contacted form the
		206	outside. This means the node cannot talk to other nodes that also have no
		207	binds, but it can still talk to all "normal" nodes).
		208
		209	If the profile does not specify a binds list, then a default of C<*> is
		210	used, meaning the node will bind on a dynamically-assigned port on every
		211	local IP address it finds.
		212
		213	=item step 3, connect to seed nodes
		214
		215	As the last step, the seeds list from the profile is passed to the
		216	L<AnyEvent::MP::Global> module, which will then use it to keep
		217	connectivity with at least one node at any point in time.
183		218
184	=back	219	=back
185		220
186	This function will block until all nodes have been resolved and, for slave	221	Example: become a distributed node using the locla node name as profile.
187	nodes, until it has successfully established a connection to a master	222	This should be the most common form of invocation for "daemon"-type nodes.
188	server.
189		223
190	Example: become a public node listening on the default node.	224	configure
191		225
192	initialise_node;	226	Example: become an anonymous node. This form is often used for commandline
		227	clients.
193		228
194	Example: become a public node, and try to contact some well-known master	229	configure nodeid => "anon/";
195	servers to become part of the network.
196		230
197	initialise_node undef, "master1", "master2";	231	Example: configure a node using a profile called seed, which si suitable
		232	for a seed node as it binds on all local addresses on a fixed port (4040,
		233	customary for aemp).
198		234
199	Example: become a public node listening on port C<4041>.	235	# use the aemp commandline utility
		236	# aemp profile seed nodeid anon/ binds '*:4040'
200		237
201	initialise_node 4041;	238	# then use it
		239	configure profile => "seed";
202		240
203	Example: become a public node, only visible on localhost port 4044.	241	# or simply use aemp from the shell again:
		242	# aemp run profile seed
204		243
205	initialise_node "locahost:4044";	244	# or provide a nicer-to-remember nodeid
206		245	# aemp run profile seed nodeid "$(hostname)"
207	Example: become a slave node to any of the specified master servers.
208
209	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
210
211	=item $cv = resolve_node $noderef
212
213	Takes an unresolved node reference that may contain hostnames and
214	abbreviated IDs, resolves all of them and returns a resolved node
215	reference.
216
217	In addition to C<address:port> pairs allowed in resolved noderefs, the
218	following forms are supported:
219
220	=over 4
221
222	=item the empty string
223
224	An empty-string component gets resolved as if the default port (4040) was
225	specified.
226
227	=item naked port numbers (e.g. C<1234>)
228
229	These are resolved by prepending the local nodename and a colon, to be
230	further resolved.
231
232	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
233
234	These are resolved by using AnyEvent::DNS to resolve them, optionally
235	looking up SRV records for the C<aemp=4040> port, if no port was
236	specified.
237
238	=back
239		246
240	=item $SELF	247	=item $SELF
241		248
242	Contains the current port id while executing C<rcv> callbacks or C<psub>	249	Contains the current port id while executing C<rcv> callbacks or C<psub>
243	blocks.	250	blocks.
244		251
245	=item SELF, %SELF, @SELF...	252	=item *SELF, SELF, %SELF, @SELF...
246		253
247	Due to some quirks in how perl exports variables, it is impossible to	254	Due to some quirks in how perl exports variables, it is impossible to
248	just export C<$SELF>, all the symbols called C<SELF> are exported by this	255	just export C<$SELF>, all the symbols named C<SELF> are exported by this
249	module, but only C<$SELF> is currently used.	256	module, but only C<$SELF> is currently used.
250		257
251	=item snd $port, type => @data	258	=item snd $port, type => @data
252		259
253	=item snd $port, @msg	260	=item snd $port, @msg
254		261
255	Send the given message to the given port ID, which can identify either	262	Send the given message to the given port, which can identify either a
256	a local or a remote port, and can be either a string or soemthignt hat	263	local or a remote port, and must be a port ID.
257	stringifies a sa port ID (such as a port object :).
258		264
259	While the message can be about anything, it is highly recommended to use a	265	While the message can be almost anything, it is highly recommended to
260	string as first element (a portid, or some word that indicates a request	266	use a string as first element (a port ID, or some word that indicates a
261	type etc.).	267	request type etc.) and to consist if only simple perl values (scalars,
		268	arrays, hashes) - if you think you need to pass an object, think again.
262		269
263	The message data effectively becomes read-only after a call to this	270	The message data logically becomes read-only after a call to this
264	function: modifying any argument is not allowed and can cause many	271	function: modifying any argument (or values referenced by them) is
265	problems.	272	forbidden, as there can be considerable time between the call to C<snd>
		273	and the time the message is actually being serialised - in fact, it might
		274	never be copied as within the same process it is simply handed to the
		275	receiving port.
266		276
267	The type of data you can transfer depends on the transport protocol: when	277	The type of data you can transfer depends on the transport protocol: when
268	JSON is used, then only strings, numbers and arrays and hashes consisting	278	JSON is used, then only strings, numbers and arrays and hashes consisting
269	of those are allowed (no objects). When Storable is used, then anything	279	of those are allowed (no objects). When Storable is used, then anything
270	that Storable can serialise and deserialise is allowed, and for the local	280	that Storable can serialise and deserialise is allowed, and for the local
271	node, anything can be passed.	281	node, anything can be passed. Best rely only on the common denominator of
		282	these.
272		283
273	=item $local_port = port	284	=item $local_port = port
274		285
275	Create a new local port object that can be used either as a pattern	286	Create a new local port object and returns its port ID. Initially it has
276	matching port ("full port") or a single-callback port ("miniport"),	287	no callbacks set and will throw an error when it receives messages.
277	depending on how C<rcv> callbacks are bound to the object.
278		288
279	=item $port = port { my @msg = @_; $finished }	289	=item $local_port = port { my @msg = @_ }
280		290
281	Creates a "miniport", that is, a very lightweight port without any pattern	291	Creates a new local port, and returns its ID. Semantically the same as
282	matching behind it, and returns its ID. Semantically the same as creating
283	a port and calling C<rcv $port, $callback> on it.	292	creating a port and calling C<rcv $port, $callback> on it.
284		293
285	The block will be called for every message received on the port. When the	294	The block will be called for every message received on the port, with the
286	callback returns a true value its job is considered "done" and the port	295	global variable C<$SELF> set to the port ID. Runtime errors will cause the
287	will be destroyed. Otherwise it will stay alive.	296	port to be C<kil>ed. The message will be passed as-is, no extra argument
		297	(i.e. no port ID) will be passed to the callback.
288		298
289	The message will be passed as-is, no extra argument (i.e. no port id) will	299	If you want to stop/destroy the port, simply C<kil> it:
290	be passed to the callback.
291		300
292	If you need the local port id in the callback, this works nicely:	301	my $port = port {
293		302	my @msg = @_;
294	my $port; $port = port {	303	...
295	snd $otherport, reply => $port;	304	kil $SELF;
296	};	305	};
297		306
298	=cut	307	=cut
299		308
300	sub rcv($@);	309	sub rcv($@);
		310
		311	sub _kilme {
		312	die "received message on port without callback";
		313	}
301		314
302	sub port(;&) {	315	sub port(;&) {
303	my $id = "$UNIQ." . $ID++;	316	my $id = "$UNIQ." . $ID++;
304	my $port = "$NODE#$id";	317	my $port = "$NODE#$id";
305		318
306	if (@_) {	319	rcv $port, shift \|\| \&_kilme;
307	rcv $port, shift;
308	} else {
309	$PORT{$id} = sub { }; # nop
310	}
311		320
312	$port	321	$port
313	}	322	}
314		323
315	=item reg $port, $name
316
317	=item reg $name
318
319	Registers the given port (or C<$SELF><<< if missing) under the name
320	C<$name>. If the name already exists it is replaced.
321
322	A port can only be registered under one well known name.
323
324	A port automatically becomes unregistered when it is killed.
325
326	=cut
327
328	sub reg(@) {
329	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
330
331	$REG{$_[0]} = $port;
332	}
333
334	=item rcv $port, $callback->(@msg)	324	=item rcv $local_port, $callback->(@msg)
335		325
336	Replaces the callback on the specified miniport (after converting it to	326	Replaces the default callback on the specified port. There is no way to
337	one if required).	327	remove the default callback: use C<sub { }> to disable it, or better
338		328	C<kil> the port when it is no longer needed.
339	=item rcv $port, tagstring => $callback->(@msg), ...
340
341	=item rcv $port, $smartmatch => $callback->(@msg), ...
342
343	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
344
345	Register callbacks to be called on matching messages on the given full
346	port (after converting it to one if required) and return the port.
347
348	The callback has to return a true value when its work is done, after
349	which is will be removed, or a false value in which case it will stay
350	registered.
351		329
352	The global C<$SELF> (exported by this module) contains C<$port> while	330	The global C<$SELF> (exported by this module) contains C<$port> while
353	executing the callback.	331	executing the callback. Runtime errors during callback execution will
		332	result in the port being C<kil>ed.
354		333
355	Runtime errors during callback execution will result in the port being	334	The default callback received all messages not matched by a more specific
356	C<kil>ed.	335	C<tag> match.
357		336
358	If the match is an array reference, then it will be matched against the	337	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
359	first elements of the message, otherwise only the first element is being
360	matched.
361		338
362	Any element in the match that is specified as C<_any_> (a function	339	Register (or replace) callbacks to be called on messages starting with the
363	exported by this module) matches any single element of the message.	340	given tag on the given port (and return the port), or unregister it (when
		341	C<$callback> is C<$undef> or missing). There can only be one callback
		342	registered for each tag.
364		343
365	While not required, it is highly recommended that the first matching	344	The original message will be passed to the callback, after the first
366	element is a string identifying the message. The one-string-only match is	345	element (the tag) has been removed. The callback will use the same
367	also the most efficient match (by far).	346	environment as the default callback (see above).
368		347
369	Example: create a port and bind receivers on it in one go.	348	Example: create a port and bind receivers on it in one go.
370		349
371	my $port = rcv port,	350	my $port = rcv port,
372	msg1 => sub { ...; 0 },	351	msg1 => sub { ... },
373	msg2 => sub { ...; 0 },	352	msg2 => sub { ... },
374	;	353	;
375		354
376	Example: create a port, bind receivers and send it in a message elsewhere	355	Example: create a port, bind receivers and send it in a message elsewhere
377	in one go:	356	in one go:
378		357
379	snd $otherport, reply =>	358	snd $otherport, reply =>
380	rcv port,	359	rcv port,
381	msg1 => sub { ...; 0 },	360	msg1 => sub { ... },
382	...	361	...
383	;	362	;
384		363
		364	Example: temporarily register a rcv callback for a tag matching some port
		365	(e.g. for a rpc reply) and unregister it after a message was received.
		366
		367	rcv $port, $otherport => sub {
		368	my @reply = @_;
		369
		370	rcv $SELF, $otherport;
		371	};
		372
385	=cut	373	=cut
386		374
387	sub rcv($@) {	375	sub rcv($@) {
388	my $port = shift;	376	my $port = shift;
389	my ($noderef, $portid) = split /#/, $port, 2;	377	my ($nodeid, $portid) = split /#/, $port, 2;
390		378
391	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	379	$NODE{$nodeid} == $NODE{""}
392	or Carp::croak "$port: rcv can only be called on local ports, caught";	380	or Carp::croak "$port: rcv can only be called on local ports, caught";
393		381
394	if (@_ == 1) {	382	while (@_) {
		383	if (ref $_[0]) {
		384	if (my $self = $PORT_DATA{$portid}) {
		385	"AnyEvent::MP::Port" eq ref $self
		386	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		387
		388	$self->[2] = shift;
		389	} else {
395	my $cb = shift;	390	my $cb = shift;
396	delete $PORT_DATA{$portid};
397	$PORT{$portid} = sub {	391	$PORT{$portid} = sub {
398	local $SELF = $port;	392	local $SELF = $port;
399	eval {	393	eval { &$cb }; _self_die if $@;
400	&$cb	394	};
401	and kil $port;
402	};	395	}
403	_self_die if $@;	396	} elsif (defined $_[0]) {
404	};
405	} else {
406	my $self = $PORT_DATA{$portid} \|\|= do {	397	my $self = $PORT_DATA{$portid} \|\|= do {
407	my $self = bless {	398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
408	id => $port,
409	}, "AnyEvent::MP::Port";
410		399
411	$PORT{$portid} = sub {	400	$PORT{$portid} = sub {
412	local $SELF = $port;	401	local $SELF = $port;
413		402
414	eval {
415	for (@{ $self->{rc0}{$_[0]} }) {	403	if (my $cb = $self->[1]{$_[0]}) {
416	$_ && &{$_->[0]}	404	shift;
417	&& undef $_;	405	eval { &$cb }; _self_die if $@;
418	}	406	} else {
419
420	for (@{ $self->{rcv}{$_[0]} }) {
421	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
422	&& &{$_->[0]}	407	&{ $self->[0] };
423	&& undef $_;
424	}
425
426	for (@{ $self->{any} }) {
427	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
428	&& &{$_->[0]}
429	&& undef $_;
430	}	408	}
431	};	409	};
432	_self_die if $@;	410
		411	$self
433	};	412	};
434		413
435	$self
436	};
437
438	"AnyEvent::MP::Port" eq ref $self	414	"AnyEvent::MP::Port" eq ref $self
439	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	415	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
440		416
441	while (@_) {
442	my ($match, $cb) = splice @_, 0, 2;	417	my ($tag, $cb) = splice @_, 0, 2;
443		418
444	if (!ref $match) {	419	if (defined $cb) {
445	push @{ $self->{rc0}{$match} }, [$cb];	420	$self->[1]{$tag} = $cb;
446	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
447	my ($type, @match) = @$match;
448	@match
449	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
450	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
451	} else {	421	} else {
452	push @{ $self->{any} }, [$cb, $match];	422	delete $self->[1]{$tag};
453	}	423	}
454	}	424	}
455	}	425	}
456		426
457	$port	427	$port
…		…
493	$res	463	$res
494	}	464	}
495	}	465	}
496	}	466	}
497		467
498	=item $guard = mon $port, $cb->(@reason)	468	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
499		469
500	=item $guard = mon $port, $rcvport	470	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
501		471
502	=item $guard = mon $port	472	=item $guard = mon $port # kill $SELF when $port dies
503		473
504	=item $guard = mon $port, $rcvport, @msg	474	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
505		475
506	Monitor the given port and do something when the port is killed, and	476	Monitor the given port and do something when the port is killed or
507	optionally return a guard that can be used to stop monitoring again.	477	messages to it were lost, and optionally return a guard that can be used
		478	to stop monitoring again.
508		479
509	In the first form (callback), the callback is simply called with any	480	In the first form (callback), the callback is simply called with any
510	number of C<@reason> elements (no @reason means that the port was deleted	481	number of C<@reason> elements (no @reason means that the port was deleted
511	"normally"). Note also that I<< the callback B<must> never die >>, so use	482	"normally"). Note also that I<< the callback B<must> never die >>, so use
512	C<eval> if unsure.	483	C<eval> if unsure.
513		484
514	In the second form (another port given), the other port (C<$rcvport)	485	In the second form (another port given), the other port (C<$rcvport>)
515	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	486	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
516	"normal" kils nothing happens, while under all other conditions, the other	487	"normal" kils nothing happens, while under all other conditions, the other
517	port is killed with the same reason.	488	port is killed with the same reason.
518		489
519	The third form (kill self) is the same as the second form, except that	490	The third form (kill self) is the same as the second form, except that
520	C<$rvport> defaults to C<$SELF>.	491	C<$rvport> defaults to C<$SELF>.
521		492
522	In the last form (message), a message of the form C<@msg, @reason> will be	493	In the last form (message), a message of the form C<@msg, @reason> will be
523	C<snd>.	494	C<snd>.
		495
		496	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		497	alert was raised), they are removed and will not trigger again.
524		498
525	As a rule of thumb, monitoring requests should always monitor a port from	499	As a rule of thumb, monitoring requests should always monitor a port from
526	a local port (or callback). The reason is that kill messages might get	500	a local port (or callback). The reason is that kill messages might get
527	lost, just like any other message. Another less obvious reason is that	501	lost, just like any other message. Another less obvious reason is that
528	even monitoring requests can get lost (for exmaple, when the connection	502	even monitoring requests can get lost (for example, when the connection
529	to the other node goes down permanently). When monitoring a port locally	503	to the other node goes down permanently). When monitoring a port locally
530	these problems do not exist.	504	these problems do not exist.
531		505
		506	C<mon> effectively guarantees that, in the absence of hardware failures,
		507	after starting the monitor, either all messages sent to the port will
		508	arrive, or the monitoring action will be invoked after possible message
		509	loss has been detected. No messages will be lost "in between" (after
		510	the first lost message no further messages will be received by the
		511	port). After the monitoring action was invoked, further messages might get
		512	delivered again.
		513
		514	Inter-host-connection timeouts and monitoring depend on the transport
		515	used. The only transport currently implemented is TCP, and AnyEvent::MP
		516	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		517	non-idle connection, and usually around two hours for idle conenctions).
		518
		519	This means that monitoring is good for program errors and cleaning up
		520	stuff eventually, but they are no replacement for a timeout when you need
		521	to ensure some maximum latency.
		522
532	Example: call a given callback when C<$port> is killed.	523	Example: call a given callback when C<$port> is killed.
533		524
534	mon $port, sub { warn "port died because of <@_>\n" };	525	mon $port, sub { warn "port died because of <@_>\n" };
535		526
536	Example: kill ourselves when C<$port> is killed abnormally.	527	Example: kill ourselves when C<$port> is killed abnormally.
…		…
542	mon $port, $self => "restart";	533	mon $port, $self => "restart";
543		534
544	=cut	535	=cut
545		536
546	sub mon {	537	sub mon {
547	my ($noderef, $port) = split /#/, shift, 2;	538	my ($nodeid, $port) = split /#/, shift, 2;
548		539
549	my $node = $NODE{$noderef} \|\| add_node $noderef;	540	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
550		541
551	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	542	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
552		543
553	unless (ref $cb) {	544	unless (ref $cb) {
554	if (@_) {	545	if (@_) {
…		…
574	is killed, the references will be freed.	565	is killed, the references will be freed.
575		566
576	Optionally returns a guard that will stop the monitoring.	567	Optionally returns a guard that will stop the monitoring.
577		568
578	This function is useful when you create e.g. timers or other watchers and	569	This function is useful when you create e.g. timers or other watchers and
579	want to free them when the port gets killed:	570	want to free them when the port gets killed (note the use of C<psub>):
580		571
581	$port->rcv (start => sub {	572	$port->rcv (start => sub {
582	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	573	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
583	undef $timer if 0.9 < rand;	574	undef $timer if 0.9 < rand;
584	});	575	});
585	});	576	});
586		577
587	=cut	578	=cut
…		…
596		587
597	=item kil $port[, @reason]	588	=item kil $port[, @reason]
598		589
599	Kill the specified port with the given C<@reason>.	590	Kill the specified port with the given C<@reason>.
600		591
601	If no C<@reason> is specified, then the port is killed "normally" (linked	592	If no C<@reason> is specified, then the port is killed "normally" (ports
602	ports will not be kileld, or even notified).	593	monitoring other ports will not necessarily die because a port dies
		594	"normally").
603		595
604	Otherwise, linked ports get killed with the same reason (second form of	596	Otherwise, linked ports get killed with the same reason (second form of
605	C<mon>, see below).	597	C<mon>, see above).
606		598
607	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	599	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
608	will be reported as reason C<< die => $@ >>.	600	will be reported as reason C<< die => $@ >>.
609		601
610	Transport/communication errors are reported as C<< transport_error =>	602	Transport/communication errors are reported as C<< transport_error =>
…		…
615	=item $port = spawn $node, $initfunc[, @initdata]	607	=item $port = spawn $node, $initfunc[, @initdata]
616		608
617	Creates a port on the node C<$node> (which can also be a port ID, in which	609	Creates a port on the node C<$node> (which can also be a port ID, in which
618	case it's the node where that port resides).	610	case it's the node where that port resides).
619		611
620	The port ID of the newly created port is return immediately, and it is	612	The port ID of the newly created port is returned immediately, and it is
621	permissible to immediately start sending messages or monitor the port.	613	possible to immediately start sending messages or to monitor the port.
622		614
623	After the port has been created, the init function is	615	After the port has been created, the init function is called on the remote
624	called. This function must be a fully-qualified function name	616	node, in the same context as a C<rcv> callback. This function must be a
625	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	617	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
626	program, use C<::name>.	618	specify a function in the main program, use C<::name>.
627		619
628	If the function doesn't exist, then the node tries to C<require>	620	If the function doesn't exist, then the node tries to C<require>
629	the package, then the package above the package and so on (e.g.	621	the package, then the package above the package and so on (e.g.
630	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
631	exists or it runs out of package names.	623	exists or it runs out of package names.
632		624
633	The init function is then called with the newly-created port as context	625	The init function is then called with the newly-created port as context
634	object (C<$SELF>) and the C<@initdata> values as arguments.	626	object (C<$SELF>) and the C<@initdata> values as arguments.
635		627
636	A common idiom is to pass your own port, monitor the spawned port, and	628	A common idiom is to pass a local port, immediately monitor the spawned
637	in the init function, monitor the original port. This two-way monitoring	629	port, and in the remote init function, immediately monitor the passed
638	ensures that both ports get cleaned up when there is a problem.	630	local port. This two-way monitoring ensures that both ports get cleaned up
		631	when there is a problem.
639		632
640	Example: spawn a chat server port on C<$othernode>.	633	Example: spawn a chat server port on C<$othernode>.
641		634
642	# this node, executed from within a port context:	635	# this node, executed from within a port context:
643	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	636	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
666	};	659	};
667	_self_die if $@;	660	_self_die if $@;
668	}	661	}
669		662
670	sub spawn(@) {	663	sub spawn(@) {
671	my ($noderef, undef) = split /#/, shift, 2;	664	my ($nodeid, undef) = split /#/, shift, 2;
672		665
673	my $id = "$RUNIQ." . $ID++;	666	my $id = "$RUNIQ." . $ID++;
674		667
675	$_[0] =~ /::/	668	$_[0] =~ /::/
676	or Carp::croak "spawn init function must be a fully-qualified name, caught";	669	or Carp::croak "spawn init function must be a fully-qualified name, caught";
677		670
678	($NODE{$noderef} \|\| add_node $noderef)	671	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
679	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
680		672
681	"$noderef#$id"	673	"$nodeid#$id"
682	}	674	}
683		675
684	=back	676	=item after $timeout, @msg
685		677
686	=head1 NODE MESSAGES	678	=item after $timeout, $callback
687		679
688	Nodes understand the following messages sent to them. Many of them take	680	Either sends the given message, or call the given callback, after the
689	arguments called C<@reply>, which will simply be used to compose a reply	681	specified number of seconds.
690	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
691	the remaining arguments are simply the message data.
692		682
693	While other messages exist, they are not public and subject to change.	683	This is simply a utility function that comes in handy at times - the
		684	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		685	so it may go away in the future.
694		686
695	=over 4
696
697	=cut	687	=cut
698		688
699	=item lookup => $name, @reply	689	sub after($@) {
		690	my ($timeout, @action) = @_;
700		691
701	Replies with the port ID of the specified well-known port, or C<undef>.	692	my $t; $t = AE::timer $timeout, 0, sub {
702		693	undef $t;
703	=item devnull => ...	694	ref $action[0]
704		695	? $action[0]()
705	Generic data sink/CPU heat conversion.	696	: snd @action;
706		697	};
707	=item relay => $port, @msg	698	}
708
709	Simply forwards the message to the given port.
710
711	=item eval => $string[ @reply]
712
713	Evaluates the given string. If C<@reply> is given, then a message of the
714	form C<@reply, $@, @evalres> is sent.
715
716	Example: crash another node.
717
718	snd $othernode, eval => "exit";
719
720	=item time => @reply
721
722	Replies the the current node time to C<@reply>.
723
724	Example: tell the current node to send the current time to C<$myport> in a
725	C<timereply> message.
726
727	snd $NODE, time => $myport, timereply => 1, 2;
728	# => snd $myport, timereply => 1, 2, <time>
729		699
730	=back	700	=back
731		701
732	=head1 AnyEvent::MP vs. Distributed Erlang	702	=head1 AnyEvent::MP vs. Distributed Erlang
733		703
…		…
743		713
744	Despite the similarities, there are also some important differences:	714	Despite the similarities, there are also some important differences:
745		715
746	=over 4	716	=over 4
747		717
748	=item * Node references contain the recipe on how to contact them.	718	=item * Node IDs are arbitrary strings in AEMP.
749		719
750	Erlang relies on special naming and DNS to work everywhere in the	720	Erlang relies on special naming and DNS to work everywhere in the same
751	same way. AEMP relies on each node knowing it's own address(es), with	721	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
752	convenience functionality.	722	configuration or DNS), but will otherwise discover other odes itself.
753		723
754	This means that AEMP requires a less tightly controlled environment at the	724	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
755	cost of longer node references and a slightly higher management overhead.	725	uses "local ports are like remote ports".
		726
		727	The failure modes for local ports are quite different (runtime errors
		728	only) then for remote ports - when a local port dies, you I<know> it dies,
		729	when a connection to another node dies, you know nothing about the other
		730	port.
		731
		732	Erlang pretends remote ports are as reliable as local ports, even when
		733	they are not.
		734
		735	AEMP encourages a "treat remote ports differently" philosophy, with local
		736	ports being the special case/exception, where transport errors cannot
		737	occur.
756		738
757	=item * Erlang uses processes and a mailbox, AEMP does not queue.	739	=item * Erlang uses processes and a mailbox, AEMP does not queue.
758		740
759	Erlang uses processes that selctively receive messages, and therefore	741	Erlang uses processes that selectively receive messages, and therefore
760	needs a queue. AEMP is event based, queuing messages would serve no useful	742	needs a queue. AEMP is event based, queuing messages would serve no
761	purpose.	743	useful purpose. For the same reason the pattern-matching abilities of
		744	AnyEvent::MP are more limited, as there is little need to be able to
		745	filter messages without dequeuing them.
762		746
763	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	747	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
764		748
765	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	749	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
766		750
767	Sending messages in Erlang is synchronous and blocks the process. AEMP	751	Sending messages in Erlang is synchronous and blocks the process (and
768	sends are immediate, connection establishment is handled in the	752	so does not need a queue that can overflow). AEMP sends are immediate,
769	background.	753	connection establishment is handled in the background.
770		754
771	=item * Erlang can silently lose messages, AEMP cannot.	755	=item * Erlang suffers from silent message loss, AEMP does not.
772		756
773	Erlang makes few guarantees on messages delivery - messages can get lost	757	Erlang makes few guarantees on messages delivery - messages can get lost
774	without any of the processes realising it (i.e. you send messages a, b,	758	without any of the processes realising it (i.e. you send messages a, b,
775	and c, and the other side only receives messages a and c).	759	and c, and the other side only receives messages a and c).
776		760
777	AEMP guarantees correct ordering, and the guarantee that there are no	761	AEMP guarantees correct ordering, and the guarantee that after one message
778	holes in the message sequence.	762	is lost, all following ones sent to the same port are lost as well, until
779		763	monitoring raises an error, so there are no silent "holes" in the message
780	=item * In Erlang, processes can be declared dead and later be found to be	764	sequence.
781	alive.
782
783	In Erlang it can happen that a monitored process is declared dead and
784	linked processes get killed, but later it turns out that the process is
785	still alive - and can receive messages.
786
787	In AEMP, when port monitoring detects a port as dead, then that port will
788	eventually be killed - it cannot happen that a node detects a port as dead
789	and then later sends messages to it, finding it is still alive.
790		765
791	=item * Erlang can send messages to the wrong port, AEMP does not.	766	=item * Erlang can send messages to the wrong port, AEMP does not.
792		767
793	In Erlang it is quite possible that a node that restarts reuses a process	768	In Erlang it is quite likely that a node that restarts reuses a process ID
794	ID known to other nodes for a completely different process, causing	769	known to other nodes for a completely different process, causing messages
795	messages destined for that process to end up in an unrelated process.	770	destined for that process to end up in an unrelated process.
796		771
797	AEMP never reuses port IDs, so old messages or old port IDs floating	772	AEMP never reuses port IDs, so old messages or old port IDs floating
798	around in the network will not be sent to an unrelated port.	773	around in the network will not be sent to an unrelated port.
799		774
800	=item * Erlang uses unprotected connections, AEMP uses secure	775	=item * Erlang uses unprotected connections, AEMP uses secure
801	authentication and can use TLS.	776	authentication and can use TLS.
802		777
803	AEMP can use a proven protocol - SSL/TLS - to protect connections and	778	AEMP can use a proven protocol - TLS - to protect connections and
804	securely authenticate nodes.	779	securely authenticate nodes.
805		780
806	=item * The AEMP protocol is optimised for both text-based and binary	781	=item * The AEMP protocol is optimised for both text-based and binary
807	communications.	782	communications.
808		783
809	The AEMP protocol, unlike the Erlang protocol, supports both	784	The AEMP protocol, unlike the Erlang protocol, supports both programming
810	language-independent text-only protocols (good for debugging) and binary,	785	language independent text-only protocols (good for debugging) and binary,
811	language-specific serialisers (e.g. Storable).	786	language-specific serialisers (e.g. Storable). By default, unless TLS is
		787	used, the protocol is actually completely text-based.
812		788
813	It has also been carefully designed to be implementable in other languages	789	It has also been carefully designed to be implementable in other languages
814	with a minimum of work while gracefully degrading fucntionality to make the	790	with a minimum of work while gracefully degrading functionality to make the
815	protocol simple.	791	protocol simple.
816		792
817	=item * AEMP has more flexible monitoring options than Erlang.	793	=item * AEMP has more flexible monitoring options than Erlang.
818		794
819	In Erlang, you can chose to receive I<all> exit signals as messages	795	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
822	Erlang, as one can choose between automatic kill, exit message or callback	798	Erlang, as one can choose between automatic kill, exit message or callback
823	on a per-process basis.	799	on a per-process basis.
824		800
825	=item * Erlang tries to hide remote/local connections, AEMP does not.	801	=item * Erlang tries to hide remote/local connections, AEMP does not.
826		802
827	Monitoring in Erlang is not an indicator of process death/crashes,	803	Monitoring in Erlang is not an indicator of process death/crashes, in the
828	as linking is (except linking is unreliable in Erlang).	804	same way as linking is (except linking is unreliable in Erlang).
829		805
830	In AEMP, you don't "look up" registered port names or send to named ports	806	In AEMP, you don't "look up" registered port names or send to named ports
831	that might or might not be persistent. Instead, you normally spawn a port	807	that might or might not be persistent. Instead, you normally spawn a port
832	on the remote node. The init function monitors the you, and you monitor	808	on the remote node. The init function monitors you, and you monitor the
833	the remote port. Since both monitors are local to the node, they are much	809	remote port. Since both monitors are local to the node, they are much more
834	more reliable.	810	reliable (no need for C<spawn_link>).
835		811
836	This also saves round-trips and avoids sending messages to the wrong port	812	This also saves round-trips and avoids sending messages to the wrong port
837	(hard to do in Erlang).	813	(hard to do in Erlang).
838		814
839	=back	815	=back
840		816
		817	=head1 RATIONALE
		818
		819	=over 4
		820
		821	=item Why strings for port and node IDs, why not objects?
		822
		823	We considered "objects", but found that the actual number of methods
		824	that can be called are quite low. Since port and node IDs travel over
		825	the network frequently, the serialising/deserialising would add lots of
		826	overhead, as well as having to keep a proxy object everywhere.
		827
		828	Strings can easily be printed, easily serialised etc. and need no special
		829	procedures to be "valid".
		830
		831	And as a result, a miniport consists of a single closure stored in a
		832	global hash - it can't become much cheaper.
		833
		834	=item Why favour JSON, why not a real serialising format such as Storable?
		835
		836	In fact, any AnyEvent::MP node will happily accept Storable as framing
		837	format, but currently there is no way to make a node use Storable by
		838	default (although all nodes will accept it).
		839
		840	The default framing protocol is JSON because a) JSON::XS is many times
		841	faster for small messages and b) most importantly, after years of
		842	experience we found that object serialisation is causing more problems
		843	than it solves: Just like function calls, objects simply do not travel
		844	easily over the network, mostly because they will always be a copy, so you
		845	always have to re-think your design.
		846
		847	Keeping your messages simple, concentrating on data structures rather than
		848	objects, will keep your messages clean, tidy and efficient.
		849
		850	=back
		851
841	=head1 SEE ALSO	852	=head1 SEE ALSO
		853
		854	L<AnyEvent::MP::Intro> - a gentle introduction.
		855
		856	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		857
		858	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		859	your applications.
842		860
843	L<AnyEvent>.	861	L<AnyEvent>.
844		862
845	=head1 AUTHOR	863	=head1 AUTHOR
846		864

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.41 by root, Sat Aug 8 21:56:29 2009 UTC vs. Revision 1.79 by root, Fri Sep 4 21:52:09 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.41 by root, Sat Aug 8 21:56:29 2009 UTC vs.
Revision 1.79 by root, Fri Sep 4 21:52:09 2009 UTC